OBJECTIVE The aim of the study was to determine the proportion of body weight borne through the lower limbs in persons with complete motor paraplegia using a standing frame, with and without the support of their arms. We also examined the effect of low-magnitude whole-body vibration on loads borne by the lower limbs. DESIGN Vertical ground reaction forces (GRFs) were measured in 11 participants (six men and five women) with paraplegia of traumatic origin (injury level T3-T12) standing on a low-magnitude vibrating plate using a standing frame. GRFs were measured in four conditions:(1) no vibration with arms on standing frame tray,(2) no vibration with arms at side,(3) vibration with arms on tray, and (4) vibration with arms at side. RESULTS GRF with arms on tray, without vibration, was 0.76 ± 0.07 body weight. With arms at the side, GRF increased to 0.85 ± 0.12 body weight. With vibration, mean GRF did not significantly differ from no-vibration conditions for either arm positions. Oscillation of GRF with vibration was significantly different from no-vibration conditions (P < 0.001) but similar in both arm positions. CONCLUSIONS Men and women with paraplegia using a standing frame bear most of their weight through their lower limbs. Supporting their arms on the tray reduces the GRF by approximately 10% body weight. Low-magnitude vibration provided additional oscillation of the load-bearing forces and was proportionally similar regardless of arm position.

The induction of complex bilateral leg muscle activation combined with coordinated stepping movements is demonstrated in patients with complete paraplegia. This was achieved by partially unloading patients who were on a moving treadmill. In comparison to healthy subjects, the paraplegic patients displayed a less dynamic mode of muscle activation. In all other respects leg muscle electromyographic activity was modulated in a similar manner to that in healthy subjects. However, the level of electromyographic activity in the gastrocnemius (the main antigravity muscle during gait) was considerably lower in the patients. During the course of a daily locomotor training program, the amplitude of gastrocnemius electromyographic activity increased significantly during the stance phase, while inappropriate tibialis anterior activation decreased. Incompletely paraplegic patients benefited from the training with respect to performance of unsupported stepping movements on solid ground. In about half of completely paraplegic patients with low muscle tone, no beneficial effect of the training was seen. This may be due to an inhibitory effect on spinal neuronal activity by drugs patients were taking (e.g., prazosin, clonidine, cannabinoids). In this study intrathecal application of clonidine drastically reduced, while epinephrine enhanced locomotor muscle electromyographic activity. The results of this study promise to be significant in the treatment of paraplegic patients.

We studied whether spinal locomotor centres of patients with paraplegia can be activated by external stimuli. In patients with complete paraplegia, coordinated stepping movements were induced by weight support and standing on a moving treadmill. The pattern of leg muscle electromyographic (EMG) activity was similar to that seen in healthy subjects although EMG amplitude was smaller. With daily training the amplitude of gastrocnemius EMG activity increased during weight-bearing phase of stepping and the degree of inappropriate tibialis anterior activity decreased. Patients with incomplete paraplegia profited from the training programme in that their walking on a stationary surface improved even when unsupported. Our results may suggest new ways to improve mobility of patients with paraplegia.

Numerous obstacles to successful regeneration of injured axons in the adult mammalian spinal cord exist. Consequently, a treatment strategy inducing axonal regeneration and significant functional recovery after spinal cord injury has to overcome these obstacles. The current study attempted to address multiple impediments to regeneration by using a combinatory strategy after complete spinal cord transection in adult rats:(1) to reduce inhibitory cues in the glial scar (chondroitinase ABC),(2) to provide a growth-supportive substrate for axonal regeneration [Schwann cells (SCs)], and (3) to enable regenerated axons to exit the bridge to re-enter the spinal cord (olfactory ensheathing glia). The combination of SC bridge, olfactory ensheathing glia, and chondroitinase ABC provided significant benefit compared with grafts only or the untreated group. Significant improvements were observed in the Basso, Beattie, and Bresnahan score and in forelimb/hindlimb coupling. This recovery was accompanied by increased numbers of both myelinated axons in the SC bridge and serotonergic fibers that grew through the bridge and into the caudal spinal cord. Although prominent descending tracts such as the corticospinal and reticulospinal tracts did not successfully regenerate through the bridge, it appeared that other populations of regenerated fibers were the driving force for the observed recovery; there was a significant correlation between numbers of myelinated fibers in the bridge and improved coupling of forelimb and hindlimb as well as open-field locomotion. Our study tests how proven experimental treatments interact in a well-established animal model, thus providing needed direction for the development of future combinatory treatment regimens.

We describe a study designed to assess a brain-computer interface (BCI), originally described by Farwell and Donchin [9] in 1988. The system utilizes the fact that the rare events in the oddball paradigm elicit the P300 component of the event-related potential (ERP). The BCI presents the user with a matrix of 6 by 6 cells, each containing one letter of the alphabet. The user focuses attention on the cell containing the letter to be communicated while the rows and the columns of the matrix are intensified. Each intensification is an event in the oddball sequence, the row and the column containing the attended cell are "rare" items and, therefore, only these events elicit a P300. The computer thus detects the transmitted character by determining which row and which column elicited the P300. We report an assessment, using a boot-strapping approach, which indicates that an off line version of the system can communicate at the rate of 7.8 characters a minute and achieve 80% accuracy. The system's performance in real time was also assessed. Our data indicate that a P300-based BCI is feasible and practical. However, these conclusions are based on tests using healthy individuals.

The objective of this study was to determine key quantitative variables in hemiplegic gait, and to correlate them with clinical abnormality, eg, degree of motor recovery. In 23 hemiplegic patients, clinical and locomotion laboratory assessments gave the following results. Two temporal gait variables, walking speed and symmetry of the swing/phase, showed a good correlation with the stage of motor recovery. Patients with greater degrees of motor recovery walked faster and more symmetrically than those with less motor recovery. None of the other temporal variables analyzed showed a significant relationship with the stage of motor recovery.

Recent studies have confirmed that regular treadmill training can improve walking capabilities in incomplete spinal cord-injured subjects. At the beginning of this training the leg movements of the patients have to be assisted by physiotherapists during gait on the moving treadmill. The physical capabilities and the individual experience of the therapists usually limit this training. A driven gait orthosis (DGO) has been developed that can move the legs of a patient in a physiological way on the moving treadmill. The orthosis is adjustable in size so different patients can use it. Actuators at the knee and hip joints are controlled by a position controller. With the DGO the legs of patients with different degrees of paresis and spasticity could be trained for more than half an hour, and physiological gait patterns were obtained.

Recent reports indicate that walking capabilities in spinal cord damaged persons significantly improve--as compared to conventional rehabilitation therapy--after intensive training of aided (Laufband) treadmill-stepping. In the present report, follow up investigations on two collectives of spinal cord injured (sci) persons are described who had undergone (Laufband) treadmill therapy either during a period of renewed rehabilitation months or years after spinal cord injury (35 chronic patients) or during their first postacute rehabilitation period (41 acute patients). Among the initially chronic patients, 20 from 25 still wheelchair-bound before the onset of (Laufband) treadmill therapy, ie not capable of raising from the wheelchair and walking without help by other persons, became independent walkers after therapy. Assessment of voluntary muscle activity in resting position before and after the period of therapy had shown only small increases in most patients, indicating the involvement of motor automatisms and better utilisation of remaining muscle function during walking. Follow-up assessments performed 6 months to 6 1/2 years after discharge from the hospital revealed that the walking capabilities achieved by (Laufband) treadmill therapy in the 35 initially chronic patients were maintained in 31 persons, in three they had further improved, in only one it was reduced. These results indicate that the improvements achieved under clinical conditions can be maintained in every day life under domestic surroundings. From 41 initially acute patients, 15 had further improved and none had reduced his walking capability 6 months to 6 years after discharge from the hospital.

Functional neuromuscular stimulation (FNS) of paralyzed muscles has enabled spinal-cord-injured patients to regain a semblance of lower-extremity control, for example to ambulate while relying heavily on the use of walkers. Given the limitations of FNS, specifically low muscle strengths, high rates of fatigue, and a limited ability to modulate muscle excitations, it remains unclear, however, whether FNS can be developed as a practical means to control the lower extremity musculature to restore aesthetic, unsupported gait to paraplegics. A computer simulation of FNS-assisted bipedal gait shows that it is difficult, but possible to attain undisturbed, level gait at normal speeds provided the electrically-stimulated ankle plantarflexors exhibit either near-normal strengths or are augmented by an orthosis, and at least seven muscle-groups in each leg are stimulated. A combination of dynamic programming and an open-loop, trial-and-error adjustment process was used to find a suboptimal set of discretely-varying muscle stimulation patterns needed for a 3-D, 8 degree-of-freedom dynamic model to sustain a step. An ankle-foot orthosis was found to be especially useful, as it helped to stabilize the stance leg and simplified the task of controlling the foot during swing. It is believed that the process of simulating natural gait with this model will serve to highlight difficulties to be expected during laboratory and clinical trials.

In paraplegic subjects who had functional transection of the spinal cord at a level between the fourth and the eleventh thoracic vertebra, independent reciprocal walking was achieved with the use of a portable microprocessor-controlled stimulator that electrically activated the muscles through percutaneous intramuscular wire electrodes. The electrodes were implanted, by means of hypodermic needles, in the flexors, extensors, abductors, and adductors of the hip; the extensors of the knee; and the plantar flexors and dorsiflexors of the ankle. The subjects had strong, selective, and reproducible muscular contractions that increased in strength during the twenty-two to forty-four months (average, thirty-two months) of training with the regimen. A basic pattern of stimulation was adapted for each individual; each step was initiated by the subject using a hand-operated switch. The subjects progressed to the use of a walker for support, and two of them were able to walk using axillary crutches. Three subjects were able to climb stairs.